It is known to form a flocked foam fabric by adhering synthetic flock fibers to closed-cell polyurethane foam as is disclosed in U.S. Pat. No. 3,528,874. Potential uses for the flocked foam are as blankets or children's garments.
The manufacture of a flocked foam fabric based on the teaching of this patent is known starting from a composite consisting of two ends of 100% 150 denier filament polyester raschel knit fabric sandwiched between two layers of 0.0625 mm polyurethane open cell foam (white or colored). A clear or colored acrylic adhesive is then applied to one side of the composite. Thereafter, fibers of nylon (a 3 den type 66 nylon cut to 0.08 inches in length as manufactured by DuPont) are flocked into the adhesive. The flocked foam is then cured at 320.degree. F. for approximately six minutes. The flocked foam is then turned over and the process is repeated on the other side. The end result is a double-sided flocked foam fabric for use as a blanket product, sold under the trademark VELLUX. (For convenience, this blanket construction will be referred to later on as a VELLUX blanket).
Based on the teaching of this patent, flocked foam blankets have been made which have upright flock fibers, forming a stand up pile. The blanket has poor drapeability and therefore is not particularly suited for apparel items. From an aesthetic point of view, a consumer would not like to wear a garment that looks like a blanket.
Due to the fibers being upright in the stand up pile, there is little abrasion resistance. The fibers can be pulled out by hand since they are only imbedded into the adhesive on the foam. Also, some of the adhesive inevitably is pulled out with the fibers, creating unsightly gaps in the fabric. This ease in pulling out fibers makes it difficult for flocked foam with upright fibers to meet industry abrasion requirements for apparel items, especially at critical wear points such as the collar, cuffs, etc.
Further, the ability to pull out the fibers is a liability, especially when the fabric is used in children's sleeping wear. Children may chew on the fabric, thereby pulling out the fibers with their teeth. This danger that a child may swallow the pulled out fibers is a risk that children's sleeping wear manufacturers may be unwilling to take.
Some techniques have been devised to change the texture or feel of the flocked fabric. For flocked poly-urethane fabric, the length of the flock fibers can be changed to produce a different grade or feel of imitation fur obtained. The longer the flock, the smoother it feels. Embossing techniques to change the feel of a flocked surface have been employed for some types of flocked foam fabrics other than those with polyurethane foam and are generally used for wall paper, rather than for apparel items.
Embossing a flocked plastisol foam surface covering is known from U.S. Pat. No. 3,591,401. The embossing is effected at 190.degree. C. by a cool embossing roll and results in permanent depressions in the foam structure and the appearance of the embossed area gives the impression of a tufted carpet. A printed decorative layer is beneath the transparent flock.
Embossing a flocked plastic foam applied to a polyester web or carrier sheet is known from U.S. Pat. No. 4,418,106. The embossing is effected by feeding the composite body between rollers at elevated temperatures to change its surface texture to have the feel of either a suede-like felted surface with deflected fibers, a woven or knitted textile surface or a leather-like surface. The carrier sheet may be secured to a polyurethane foam backing.
Embossing modacrylic flocked polybutadiene foam to obtain a permanently flattened flock surface in the embossed recesses is known from U.S. Pat. No. 4,362,773. To obtain colored patterns, flocks with dissimilar patterns are used. This patent also teaches away from imbedding nylon flock at elevated temperatures and pressures in polyurethane foam by describing such a process as being unobtainable with its high temperature welder.
Imbedding synthetic fibers into a polyurethane adhesive on a wool fabric at elevated temperatures and pressures is known from U.S. Pat. No. 3,262,128, which produces a fabric having improved drapeability, abrasion resistance, water repellency and strength. After the desired imbedding is obtained, the flock fibers straighten to their pre-pressed state. Thus, the flock fibers are not permanently deformed.
In addition to the texture or feel of the fabric, another major concern in the apparel industry is color consistency.
Color consistency is crucial in the apparel industry. Unlike blankets which are sold individually and typically not shown together, apparel items are sewn together at seams and commonly sold together. Thus, even slight differences in the color at the seams or between left and right apparel "pairs" (e.g. slippers) will create a commercial disaster even for an otherwise excellent apparel fabric.
Some ways to achieve consistency in color on flocked fabric include selectively applying fibers of dissimilar colors or applying a flock dissolving agent containing a dye. Such methods are time consuming and expensive in that they require that special care be taken in first obtaining the different colored fibers or batches of dissolving agents of various dyes and then selectively applying the colors to avoid inadvertent mixing of dissimilar colors. The use of the dissolving agent can lead to differences in the feel of the flock due to differences in the shortening of the flock if the process is not carefully controlled.
There is a limited number of colors that are commercially available as "off the shelf" items for colored flock. Unless an additional investment is made to recolor the commercially available flock or pay a premium for custom colored flock, garment manufacturers are limited to the colors which are commercially available.
Before adhering the flock to the foam by an adhesive in the acrylic latex family, in accordance with the teaching from the Spencer patent, the polyurethane foam layer is fed through printing equipment to achieve a colored pattern. Alternatively, a colored adhesive is applied. Such techniques, although simpler to do than selectively applying colored fibers or dyes, create color inconsistency problems due to the nature of polyurethane foam manufacture.
Polyurethane foam is manufactured by foaming polyurethane which requires expanding a ball (e.g. a baloney) of polyurethane with air, thereby generating air bubbles, which vary in size from the inside to the outside of the ball. Due to the presence of these bubbles, the rate of absorption of the colored adhesive at different areas of the ball varies, thereby preventing the attainment of uniformity of color. Each production lot of the foam therefore varies in color from the color of the next lot because the adhesive color matching is not precise.
In addition, the foam must be cut to its correct thickness, which is subject to cutting tolerances. For instance, if the foam is cut to a 0.06 inch thickness, experience has shown that this thickness may vary by as much as 0.01 inches. This difference in thickness creates differences in the amount of the color adhesive which is absorbed at different areas of the foam, thereby adversely affecting the attainment of uniformity of color.
Further, polyurethane is very sensitive to exposure to light and the gases in the air, which tend to discolor the polyurethane over time. This discoloring effect makes it impossible for any given production lot of the foam to have the exact color as the next.
Even if these color inconsistency problems were overcome, there would still remain the problem that the coloring lies beneath the flock. The color of the fabric will appear to be that of a blend of colors as between the color of the flock and the coloring beneath the flock. For instance, the apparent color of a fabric having white flock on a black dyed foam will appear to be a shade of gray. Further, the blending of the flock and foam colors make it difficult to achieve desired pure colors. The color underneath the foam will not appear to be as clear or crisp when viewed through the flock.
To obtain a dyed blanket, it is necessary to cut the roll of fabric material to blanket size, dye the blanket individually and then dry it individually in a dryer. Practically speaking, drying the entire roll of material cannot be done since the dryer required would be too huge. For apparel items, where the fabric is rolled out on a table and then into different-sized pieces that are to be sewn together at seams, it is too cumbersome and not practical economically to dye each individual piece separately.
It is known to use a dry ink transfer process for printing onto wovens or knits of synthetic fibers such as polyesters, polyamide, acrylic, triacetate and acetate. This process involves feeding together a knit or woven fabric and specially inked thermal paper between rollers at elevated temperatures and pressures such that the ink is transferred onto the knit or woven fabric.
Especially for apparel items, it would be desirable to provide a flocked polyurethane foam fabric that provides better drapeability, hand, appearance wearability, abrasion resistance, wrinkle resistance, thermal insulation characteristics and color consistency than does flocked polyurethane foam fabric with upstanding flock fibers so that the fibers are not easily pulled out.